Automatically fed furnace



vJan. 29, 1946; H. w. SANFORD ET A-L 4 2,393,710

' AUTOMATICALLY-FED FURNACE Filed Dec. 8, 1941 8 Sheets-Sheet l I 77 ,lA f/ BB f 2;.

R I v My Jan. 29, 1946. H W. SANFORD Em; 3,7

AUTOMATICALLY FED FURNACE 'Filed Dec. 8, 1941 8 Sheets-Shet 2 Jan.- 29,1946. 'H. w. SANFORD ET AL 2,393,710

' AUTOMATICALLY FED FURNACE I Filed Dec. 8, i941 8 Sheets-Sheet 5 AErica/vans Jan. 29, 1946.

H. w. SANFORD ET AL AUTOMAT I CALLY FED FURNACE Filed Dec. 8, 1941 8Sheetsl-Sheet 4 Jan. 29, 1946. H. w. SANFORD ET AL ,3

7 AUTOMATQECALLY FED FURNACE Filed Dec. 8, 1941 s She ets-Sheet '5 [W Fg By Q/ H. W. SANFORD ET AL AUTOMATICALLY FED FURNACE Jan. 29, 1946.

Filed Dec. 8, 1941 v 8 Sheets-Sheet 6 Patented Jan. 29, 1946 UNITEDSTATES PATENT OFFICE:

.2,39s,71o. AUTOMATICALLY FED FURNACE Hugh WQSanford and AlfredFfSanford, II, Knox'v'ille, Tenniys'aid Alfred F. Sanford, II, asslgnorto said liu'gh W. Sanford h i Application. December 8, 1941, Serial No.422,188 V 33 Claims; (cl. 110-32) The invention relates generally tofurnace structures adapted for the burning of solid fuel and primarilyseeks'to provide a novel furnace structure embodying a longitudinal firepot open or openable at one end for ash and clinker discharge,reciprocable'means for positively forcing fuel and ash along the firepot toward said discharge end, means for feeding charges of fresh fuelso that a column of fresh fuel will reach approximately to the bottom orgrate of the combustion chamber, and in front of and adjacent to theforcing means, power means for operating the fuel feeding meansand-theforcing means, and means for so timing andcontrolling theoperation of the fuel feeding means and the forcing means as to meet allheat demands and yet assure against burning out of the fire, thedischarging of any substantial quantity of unburned fuel with the ashes,and to prevent the heat waste that occurs when ashes are burned intoclinkers.

An object of the invention is to provide in a furnace of the characterstated a dual timing control effective to automaticallyprovide apredetermined definite number of fuel charge feedings in a giveninterval of time for maximum combustion operation of the furnace, andtoprovide a variable predetermined lesser definite number of fuel chargefeedings in a like interval of time for idling operation of the furnace.

Another object of the invention is to pr-ovide a furnace embodying adual timing-control of the nature stated including two fuel-charge feedtiming devices and thermostatic or pressure control means for renderingsaid devices selectively effective according to heat: demand.

Another object'of the invention is to provide a furnace of the characterstated in which the dual timing controls and additional control meansareso cooperatively arranged that the latter will dominate control when afresh fire is being started and will cause continuous fuel chargefeedinguntil a predetermined congestion of fuel mass is established in the firepot, after which normal control will be taken over by said dual timingcontrols and maintained thereby until such time as rapid fuel combustionmay have reduced fuel mass congestion to a predetermined minimum atwhich time continuous fuel charge feeding will again be temporarilyoccasioned.

Another object of the invention is to provide a furnace of the characterstated in which said additional control means includes a novel doorstructure yieldably obstructing discharge of ash and clinkers, andcontrol switch means actuated by movement of thedoorr g Another objectoflthe invention is to provide a furnace of the character stated inwhich is embodied a fire pot flared at its side walls and offset at itsbottom so as to reduce friction resulting fromfuel mass contact and alsoeliminatedanger of clogging the fuel mass forcing means.

Another object of the invention is to provide novel means for directingprimary air into the combustion chamber within the fire pot throughnovel non-clogging openings in the bottom and side walls of said firepot.

Another object of the invention is to provide novel means for providingsecondary air above the fuel combustion zone in the fire pot.

Another object of the invention is to provide novel means for causingsmoke and gases passing off above freshly fed green fuel locatedexclusively in the receiving end of the fire .pot to be directed towardthe opposite end 'of the fire pot and over incandescent fuel in thecombustion zone, thereb to be consumed over said combustion zone.Another object of the invention is to provid novel means for causing theprimary and secondary air to be preheated before effective deliverythereof.

Another object of the invention is to provide a furnace of the characterstated in which the fuel feeding means and the fuelmass forcing meanscomprise a common prime mover, a reciprocable pusher, a reciprocablefeeder slide, a crank shaft driven by the prime mover, and connectionsbetween said pusher and slideand said crank shaft for reversely andpositively reciprocating the pusher and slide.

Another object of the invention is to provide means of the naturestatedlfor positively reciprocating the pusher andthe slide in which thedriving'connections canbereadily adjuste'd'to vary the effective strokemovements of the slide.

Another object of theinvention is to provide means of the characterstated for adjusting the effective stroke movements of the fuelfeedingslide including devices for causing all variations in the'strokeof the slide to b'eieifected at the retraction end of the slide stroke,thereby to cause the slide always to be advanced .Tto a predeterminedposition regardless of stroke adjust; inent. r -31:

Another objectxof the invention is to provide a fire pot of thecharacter stated including. an ash discharge door for yieldablyresistingdischarge of ashes therethrough as a result of pressure. exerted onthefuel mass by thefuel.

mass pusher, and means for varying the amount away andinsectionr 1closely spaced yieldable fingers which will permit lump passage withoutfree outpouring of finer fuelparticles.

Another object of the invention is to p ovide a devices for use in afurnace adapted for the burn-' in a fuel feeding means of the characterstated a novel swingable fiap displaceable during each fuel chargefeeding but which normally serves to protectfuel in the hopper fromradiantheat' from the combustion chamber;

Another object of the invention is to't'itvie in a furnace of thecharacteristated a novel fuel mass pusher structure, novel means forpreventing clogging of the pusher, and novel means for ing slide and thefuel mass advancing pusher in V predetermined positions, preferably butnot necessarily with the slide retracted and the pusher in its advancedposition. v v Another object of the invention is to provide in a furnaceof the character stated a fanfor supplying air for the combustion of thefuel, and controlmeansfor causing the fan to oper-. ate continuously,while the furnace operation is under the control of the fast timerequipment, and intermittently when the furnace operation is undercontrol of the slow timer, that is to say when idling.

With the above and other objects in view which will more fully appearthe nature of the invention will be more clearly understood by followingthe description, the appended claims, and the several views illustratedin the accompanying drawings.

In the drawings:

Figure 1 .is a central vertical longitudinal sec tional view of afurnaceembodying the invention.

Figure 2 is a vertical cross section'ta-ken on the line 2-2 on Figural.r

Figure 3 is a vertical crosssection takenon the line 3--3 on Figure 1.

Figure 4 is a horizontal section taken on the line 4-4. on Figure 1.

Figure 5 is a right side elevationof the furnace.

Figure 6 is. .a fragmentary end elevation of the fire pot showing themounting of the ash door actuated switches.

Figure :7 is a fragmentary. right side elevation of the parts shown inFigure 6.

Figure 8 is a fragmentary vertical crosssection showing a modified formof the arch providing a restricted passage for smoke andgases over theincandescent fire bed.

Figure 9 is a vertical cross section taken on the line 9-4 on Figure 8.

Figure 10 isa fragmentary enlarged detail horizontal section taken onthe line] 11-10 on Figure 1 through the lower pivot mounting of the fuelfeeding slide reciprocating lever.

Figure 11 is an enlarged front face view of one of the limit switches. v1

Figure 12 is a right :end elevation of the limit switch shown in Figure1l,J-parts being. broken Figure 13 is a rear elevation of the limitswitch shown in Figure 11, an adjustment of the switch position beingindicated in dotted lines.

Figure 14 is an enlarged side elevation showing the position switchmounting.

Figure 15 is a vertical cross section taken through the axis of theposition switch actuatf a i Figure .16 is a diagrammatic viewillustrating the electrical connections of the'var'ious control ing ofother than anthracite coal, the ash discharge gate operated switchesbeing omitted.

Figure 17 is a view similar to Figure 16 and illustrates the connectionof the control devices in a furnace adapted for the burning ofanthracite.

Figure '18 is a view similar to Figure 16 and ill'ustrates theelectrical connections of the various control devices for use in afurnace in which th'e'as'h discharge gate operated switches areincluded. V

In the, example of embodiment of the invention herein disclosed, 5'designates the floor or bottom upon which rests an open base .framet.The framev is-closed at-the sides and rear :by a sheet met-alcasingstructure 1, and its open front is closed by an ashremoval door "8. Thecasing 1 is, provided with a removable side panel 9 through which access,may be had to the interior of the basestructure, and the mechanismtherein.

A fire pot generally designated I0 is mounted inzspaced relationwithinthe-base frame, said fire pot including, side walls H which are flared,

slightly in the forward direction and which depend from supportingflanges l2 resting upon the base frame 6. Thefire pot also includes a.fire bed supporting bottom generally designated I3 and e the staggeredrelation best illustrated in Figure 4,

and these cross .bars or .sections are formed. to provide an overhangingroof or hoodstructure I6 overlying each of the ports. It will beobserved that the roofor hood structures are projected forwardly therebyto cause the ports to open upwardly and forwardly into the fire bed, or,in other words, in the direction in which the fuel mass is advanced overthe supporting bottom IS in a manner later to be described. Theparticular construction and arrangement of the fire potcbottom crossbars provide other advantages. By proper regulation of. the size andlocations of the openings or air ports IS in the bottom, it is possibleto introduce the relative amount of air desired in each different partof the fire pot. Thus it is possible to either intensify or retard thecombustion rate at will and in any certain part of the fire pot relativeto someother part. This feature will be found very advantageous.The-hood structures It also tend to break up the fuelmass which passesover the fire pot bottom from the receiving end thereof to the ashdischarging end thereof and to permit the easier passage of the airthrough the fuel mass.

It is also preferred that the fire pot bottom be inclined downwardlytoward the ash discharging end thereof inthe manner illustrated in Fiures l and 8 of the-drawings. Bythus inclining in the mannerhereinbeforewstated, less resistance to movement of the fuel mass withinthe fire pot is offered and the effort necessary to be expen'dedby themotor which drives the pusher 24 is materially reduced. It is to beunderstood that the amount of thefiare of the side walls and the amountof the forward and downward inclination of the fire pot bottom may bevaried according to-the nature of the particular installation and thetype of fuel to be used. The use of an inclined bottom in the fire potwill be found very advantageous in installations where it is desirableat times to maintain a long but thin fuel bed. 1 a

It will be observed that the fire pot is longitudinally directed andpreferably substantially u-shaped with the front end thereof throughwhich ashes and clinkers are'adapted to be discharged sloped as at IT.The sloped, ash and clinker discharging end of the fire pot is equippedwith a gravity closed ash discharging door I 8 which is hingedlysupported at its upper end as at I-9. An adjustably mounted weight 2!]is carriedby the door l8 at its lower end, and by adjustment of thisweight the resistance to opening of said door can be varied to suit thevariations in operating conditions occasioned by the use of differentforms of fuel, and different lengths of fire pot. It is also possible tovary the depth of the fire bed in the fire pot for a certain length byincreasing or diminishing the resistance to opening of the ashdischarging door, and by varying the downward slope of the bottom of thefire pot. It should be understood that for a certain downward slope thegreater the resistance to opening of saiddoor, the greater will be thedepth of the fire bed being advanced over the fire bed supporting bottomto be ultimately discharged in the form of ash and clinkers through thedischarge door l8. However, the height of the fuel bed is neverpermitted to be greater than the height of the pusher plate 24.

Primary air for the combustion "of the fuel is delivered through thebottom ports l and it will also be observed by reference to Figures 1and 2 of the drawings that the side walls ll of the fire pot also areprovided with longitudinal, primary air admitting ports 2| whicharedisposed just above the bottom l3. The side ports 2| are outwardlyand upwardly inclined and have air scoop ledges 22 bordering theirexteriors in position for guiding primary air thereinto. The

ledges 22 also are effective to prevent falling of bottom and sides toprovide a tunnel 23, and in order to provide for the advancement of thefuel mass through the fire pot and the advancement of suitably timedfresh charges of fuel according to the present invention, a fuel masspusher 24 is reciprocably mounted in this tunnel. See Figures 1 and 4.The pusher 25 comprises an upwardly and forwardly inclined pusher platewhich terminates at its lower edge in a downwardly and forwardlyinclined and sharpened step portion 25. The sharpened step preferablydrags over the floor of the tunnel 23 during reciprocation of the pusherand is effectiv to dislodge any fuel tending to adhere to the tunnelfioor. At its upper extremity the pusher plate merges into ahorizontally and rearwardly extended shelf portion 25 which effectivelyserves to support any fuel falling thereon during advancement ofthe-pusher plate and to prevent falling of fuelsbehind said plate. Beingupwardlyand forwardly in clined, the pusherplate 24 serves to shape thefuel mass engaged thereby in the fire pot and tends also to keep thefire bed at a low level. Thus there is small possibility that the firebed'will build up and tend to flow over onto the top 26 of the pusherplate during its forward movement.

It will be observed by reference to Figure lof the drawings that thefloor 21 of the tunnel 23 which is engaged by ,the lower, step portionof thepusher plate, is disposed at a slightly higher level than the mainfire bed supporting surface of the fire pot bottom I3. By thusoffsetting the fire pot bottom it is more difficult to cause a'jamming-of the pusher 24 by the adherence of fuel to the fire bottom orby reason of the pres-,- ence of jammed clinkers in the bottom of thefire pot.

It will also be observed that the tunnel floor 21 is provided with adischarge opening 23 disposed just behind the limit of retraction of thecpusher plate 24, and this opening will serve to discharge any bits offuel which might find their way past the pusher plate. It should also beobserved that the rearmost primary air intake ports P5 are disposed wellahead of the most advanced position of the pusher plate 24 asillustrated in Figure 1, By reason of this arrangement of the parts thedanger of sticking of fuel to the fire pot bottom just in advance of thepusher plate is reduced to a minimum and leakage of primary air andsmoke rearwardly past the .pusher plate is effectively guarded against.

An upper cross wall 29 is provided at the rear of the fire pot and thiscross wall preferably but not necessarily is disposed on an upward andforward inclination as indicated in Figure 1 and in position for liningup with the'pusher plate 24 when that plate is in its most advancedposition as illustrated in said Figure l. The upper cross wall 29 servesto prevent coal from falling over the front face of the pusher plate 24when it'is in its most advanced position, and this plate also serves toprotect the fuel in the hopper from radiant heat from the fire bed.While it is preferred that the wall 29 be inclined in the manner stated,it is not necessary that this wall be so inclined.

The pusher is equipped with a plunger 30 which extends rearwardly fromthe center thereof and is slidable in a bearing 3| provided therefor andguiding same, and preferably supported'upon the tunnel floor 21. 3

The fire pot generally designated ll! opens upwardly'into a generallysquare body 32 which in this particular illustration is surrounded by asheet metal casing 33 forming an air space 34 in which air is heated bycontact with the heated walls of said head. Air thus heated in the space3415 directed to rooms or other spaces tobe heated through a' duct orducts 35 and may be returned through a duct or ducts 36 for reheating.It is to be understood that a separate circulating fan may be employedfor forcing circulation of this air, but since the provision of theseducts and circulating fans of this nature are well known in the art, itis thought to be unnecessary to illustrate the fan in detail herein.

A flue 31 leads upwardly from the rear por-.

tion of the body 32, and a fire brick dome 38 is disposed across therear portion of the head 32 between the fire pot and the flue in themanner best illustrated in Figure 1. The dome 38 extends "over slightlym'ore than the rear. half por l tionof the fire pot, and a transverse.flre brick wall or arch '39 depends from the-foremost edge of this domeand terminates just a few inches above thelfire pot so :as to provide arestricted passage or space 40 between the lower extremity of said archand the fire bed. By reason of the. provision of the dome 38 and thearch 39 smoke :and

gases arising fromthose fresh fuel charges which are of'a volatilenature and deposited at the rear end :of the fire pot in-a manner laterto be described curl upwardly and forwardly under the j dome .38 and arethen forced downwardly into contact with the incandescent fuel bed whilepassing through the restricted passage 40 toward the flue 31..SeeFigure 1. .In this manner the [gases and smoke are effectivelyheated so that the introduction of fresh oxygen in the form :of

secondary air willcomplete their combustion, and the improved furnaceoperates substantially in smokeless fashion.

An ash collecting pan 41 is supported on the fioor beneath the advanceor discharge end of the firepot Ill and ashes, and perhaps some Thepusher tunnel '23 is'in part defined by .a

7 top wall 42 which forms a slide support for a fuel c'linkers,accumulating in this pan can be convenien-tly'removed through the ashdoor 8.

feeder slide 43 which is horizontally reciprocable in-a feedway-44provided in the manner best illustrated in Figures 1 and 3 of thedrawings.

The feedway 44 is disposed beneath the delivery opening of a fuel hopperor magazine 45 having a downwardly and forwardly sloping rear bottomwall 46, downwardly and inwardlyslop'ing 1 side bottom walls 41., and avertical front wall 48.

It will be obvious that so long as a supply of fuel remains in thehopper or magazine 45 the lower extremity of the hopper and the feedw ayin advance of the slide 43 will be filled with fuel, and a charge ofthis fuel will be delivered from the hopper at each forward movement ofthe slide 43.

Fuel is yieldably retained in the lower portion of nature of atransverse supporting bar 49 and preferably depending, closely spacedand fairly flexible spring steel fingers '51! which extend down intoclose proximity with the slideway bottom 42.

largest dimension of the largest lump of fuel 3 the hopper by ayieldable gate structure in the a 4 These fingers are considerablylonger than the v likely to be fed into the fire pot so that the fingerswill not be bent out abruptly and get per-'- manently set out of shapewhen the top of the supporting bar 49 is securely fastened to the mainstructure. Each time the fuel feeding slide 43 1 is advanced the fingers50 yield to permit passage of a charge of fuel therethrough, and whenthe slide is retracted these fingers return to, or sub- Figure 1. Byreason of the provision-of-this novel stantially to the verticalposition illustratedln form of yieldable gate, coal .lumps can be forcedthrough the gate and the individual fingers will large piece and at thesame time to prevent outpouring of fine fuel particles'at each sideofrthe discharging lump. The yieldable gate 50 permits thexintendedfeeding of solid fuel charges without forcing the slide 43 to break upany lumps which might be present in the coal. In other words, the

1 closely spaced yieldable fingers 5.!) permit the pasmotorlcapable ofcrushing lumps, and italso yield in conformity with the shape of theextra assume makes it possible for foreign matter such as railroadspikes orrocks to be passeduthrough the furnace and discharged therefromwithout trouble or damage. v

Just in front of the yieldable gate structure 49, 50 :there isprovided-a solid flap 5] which is hingedly supported at its upper edgeacross the f-eedway. This flap also yields at advancement of the feedslide, 43 to permit passagethereu-nder of each charge of fuel, anduponretraction of the slide this flap returns to its normal positionillustrated inFigure .1. Positioned in the manner illustrated, the flap5| effectively serves to protect the gate 56 and the fuel inthe feedway44 and "the hopper against direct contact of heat from the combustionchamber in the fire pot Ill. The fuel charges delivered by theintermittent advancement of the feed slide 43 always .are less in volumethan the volume of the receiving space provided therefor by retractionof the pusher plate 24,. Each such charge is deposited by the forwardmovement :of the slide 43 and deposited generally speaking either infront of the retracted pusher face 24 or on top of the shelf portion .26and in front of the downwardly inclined wall portion :52 and in suchfashion that when the pusher 24 is completely retracted into the advanceportion of the tunnel space 23, all of the fresh fuel charge will .belocated in front of the pusher 24. Then as the pusher 24 advances thisfresh fuel charge is forced forwardly by said pusher into the rear endof the fire pot and against the fuel mass therein in the mannerillustrated in Figure 8 of the drawings. It will be noted that each fuelcharge thus forced into the fire pot occupies a substantiallyverticallayer reaching down to the supporting surface of the The fuelfeeding slide 43 includes a rearwardly and horizontally extended topwall 53, and the bottom edge thereof is equipped with a forwardly anddownwardly sharpened step 54 similar in formation function with the stepportion 25 of the pusher plate v24. The top wall :53 of the feeder slide43 serves to support fuel in the hopper bottom during each forwardprojection of the slide 43 and by this means effectively preventsdischarge of fuel behind the slide proper 43.

The fuel feeding slide 43 is equipped with a plunger 55 which extendsrearwardly from the center thereof and is slidable in a bearing 56provided therefor and is preferably supported upon the top wall 42 ofthe pusher tunnel.

Access to the fuel feedway 44 may be had through a suitable door 5'! inthe casing structure and best illustrated in Figure 5 of the drawings.

It will be observed by reference to Figures .1 and 2 of the drawingsthat a primary air casing 58 is suspended beneath the fire pot I 8. Thiscasing is formed to provide a horizontal duct 59 extending in spacedrelation to the fire pot bottom 13 and beneath all of the air ports l5therein, but it will be noted that this duct is closed across :itstopportion and does not deliver air directly into said P H BSL A fan 60delivers air into the rear end portion of the duct 59, and this fan isdriven by a separate motor Bl.

Side plates 62 extend upwardly from the lateral extremities of the duct59 and in laterally spaced relation to the side Walls ll of the firepot. Intermediate side plates 63 are disposed in spaced relation betweenthe vside plates '62 and the adjacent fire pot'side walls II, and theduct 59 communicates upwardly into the space pro-v vided between theadjacent side'plates 62 and 63. It will be'observed by reference toFigure 2 of thedrawin'gs that the intermediateplates terminate at 64well below thehorizontal support ing flanges l2 of the fire pot, and byreason of the particular relation of these side plates, .9, tor tuouspassage 65 is provided through whichpri-i mary air, forintroduction'into the bottom of the fire pot through the side ports 2|and the bottom portsl5 first passes upwardly "at each side from thebottom duct 59 between the spaced plates 62 and '63 at the-respectivesides,*,and thence downwardly between the plates 63*and the respectiveside walls H of the fire pot." In passing downwardly the air isscoopedjinto' the side openings 2| by the deflectors 22, and the. airwhich passes these deflectors passes into the space 66 directly beneaththe fire pot bottom l3 and thence upwardly'and forwardly through theports l5. By directing the primary air in the particular manner stated,this air is preheated while passing in contact with the fire pot sidewalls I l, and this contactserves the double purpose of tending to coolsaid side walls;

A secondary air duct 61 leads from the main bottom duct 59 into the firebrick wall or arch 39 where it delivers into a manifold-68 provided insaid arch; From the manifold,- the secondary air is delivered through amultipleiof individual ducts 69 through the bottom edge of the Wall orarch 39 and intothe'restricted s'pace'immediately beneath said arch. SeeFigures 1 and 2. It should perhaps be noted here 'that for anthracitefiring,'no secondary air -is needed; This means of providing secondaryair is' designed primarily for furnaces in which the burning of volatilebituminous coal is intended. The casing 33 is also provided with a sidedoor "Ill through which access may be had into the interior of the domestructure above'the 'fire pot for fire inspection purposes, for thelaying'of'a new fire, or for the replacing of the fire arch or crosswall 39. l

As an example of means for suitably reciprocating the pusher and thefeed slide, there is illustrated a crank shaft H which is rotatable inbearings 12 provided therefor and supported on the floor 5. Rotation maybe imparted to'the crank shaft H by a motor 13 and the speed of themotor is reducedthrough suitable reduction gearing generally designated"so that the crank shaft is rotated preferably at approximately onerevolution every two minutes. It is found by' experience that'the slowrotation of the crank shaft with the consequent slow movement of thepusher 24 and the feed slide 43 provides bettenc'ombustion conditionsinvthe fire box. The crankshaft is provided with a relatively shortcrank 15 which 'is effective for driving the pusher 24, and with alonger crank l6 which is effective for driving the fuel feed'slide 43.The particular crank shaft speed referred to is'but an illustrativeexample effective to impart reciprocation to the pus'h'er and-thefeedslide at'a maximum rate of thirty reciprocations perh'our, and isnot to becons'true'd as a limitation upon the nature or scope of theinvention.

,While crank shaft, lever and link connections are herein shown anddescribed as the means for imparting positive reciprocation to thepusher 24 and the slide 43, it is to be understood that any otheracceptable means can be employed for im-' parting the desired fuelfeeding movements to these parts.

" The'pusher plunger 30 is slot and .pin connected, as at 11, with theupper end of a lever 18 which is fixedly pivoted at its lower end, as at19, and is pivoted intermediate its ends, as at 80, with a thrust link8! connected with the crank 15.

The feed slide plunger is slot and pin connected; as at 82, with theupper end of a lever 83 which hasa lost motion pivot connection at itslower end in a variable length slot 84 and is pivotally connectedintermediate its ends, as at 85, with a thrust link 86 which isconnected at its forward end with'the crank 16. The slot 84 is formed ina fixed support 84a and the length of the slot can be varied byadjustment of a screw 8412. It will be obvious that as the crank shaft His rotatedthe pusher 24 and the fuel feeding slide 43 will be reverselyreciprocated. In other words, each time the pusher plate 24 is advancedto its foremost position illustrated in Figure 1, the fuel feeding slide43 will be retracted to its rearmost position illustrated in Figure 1,and vice versa. By reason of the provision of the pivotal connection atthe lower end of the lever 83 in the lost motion slot 84, the forwardstroke limit of the slide 43 will remain constant at the juncture of thehorizontal wall portion 42 and the forwardly and downwardly inclinedwall portion 52, while the retraction stroke limit of this slide may bevaried by adjustment of the screw 84b, or; in other words, vbyadjustment of the length of the slot. It will be understood that eachtime the link 86 is thrust rearwardly it will move the lower] endof thelever 83 along the slot 84 without imparting movement of retraction tothe slide'43 until the pivot pin at the bottom of the lever 83 engagesthe variable end of the slot, namely, the screw 842), at which time thelost motion movement of'the lower end of the lever will be stopped andmovement of the lever 83 will become efiective. to impart movement ofretraction to the slide 43. It will be obvious that the shorter thelength of the slot 84, the longer will be the length of the effectivestroke imparted to the slide 43, and the longer the slot the greaterwill be the lost motion movement of the lower end of the lever 83 andthe shorter the effective or fuel feeding stroke imparted to the slide43.

By definitely fixing the forward limit of the slot '84, the forwardstroke limit of the slide movement is fixed at thepoint hereinbeforedescribed, and thus, regardless of the length of feed strokebeingimpartedto the slide 43, the forward liimt ofthe slide movement is fixedat a point where it will surely remove all coal from the advanceportionof, the wall 42 and thereby overcome any tendency of coal lumps to holdthe flap 5! open so that'such coal might become ignited by radiant heatfrom the fire pot and burn up into the hopper.

A timing switch'setting collar 81 is adjustably secured to the pusherplunger 30 in the manner best illustrated in Figuresll and 13 of thedrawings. This collar has two actuator fingers 88 projecting in oppositedirections laterally therefrom in position for actuating or settingthetwo timing switches which form a part of the means 1 recesses 88 formedin the front Wall 92...

6 asses-1c for automatically controlling the furnace, it beingunderstood that one of these switches 'servesto I provide for apredetermined definite number of fuel charge feedings and advancementsin a given interval of time for maximum combustion operati'on of thefurnace, and the'other-th'ereof serves toprovidefor a predeterminedlesser definitenumber of fuel charge. feedings: and advanceswitchportionthereof, a detailed description of one of the units: will. suffice forbothv of them;

Each timer unit; comprises a bracket having a Base 9!, an upstandingfront wall 92, and a parallel rear 'wall'93, andz is rigidly supportedabove the floor as at; 94. A cross shaft; 95 is rotatably mounted in;the bracket and is extended through the front. wall 921* and: provided.with a position adjusting" handle 86. The handle: car'- ries a springpin 91 which may be engaged in one of a pluralityof selective positionretaining Acasing 99 is secured upon.- andmovable with the shaft 95, andan'independent rotor we is rotatably mounted in and projects: rearwardlyfrom the casing; ,The rotor I200 has; a crank arm 1M attached thereto,and this arm depends in position ,for being engaged and moved rearwardlyby the respective one of'the actuator fingers 88 each time the pusherplunger 38 moved. rearwardly during a retraction of the pusher.

Each rearward movement of the arm it; serves to store energy in aspring, in which is mounted within the casing lie-and return move ment.of: the arm HM urged by the spring I02 controlled by an escapementmechanism H13 mounted within the casing. Thus; each rearward movementof. the arm WE occasioned by retraction of. the pusher plunger 3! israpid, but return i or forward movemnt of the arm is very slow un- 55and this; switch is: of the well known type in which the circuitcontrolling contacts are normally spaced apart or open. The switch con-1 taots are caused to! engage: to completea circuit throughthe switch.only when'the switch plunger Hi5 is pushed inwardly. In order toaccomplish this a disk Hi6 is secured torotate with the rotor 1 lot! andis provided atone point on its periphery with an. actuator hump or'camportion Hil which is engageable with a roller H38 carried at. the

free end of a. y-ieldalaile. arm- Hlfl which overlies the plunger l5 andis secured to the.- switch as at lto.

After each crank arm Hit is moved rearward-1y His. After it. hasreturned a predetermined distance, determined by placement of. the shaft95 and the switch Hi4 movable therewith, the hump 1 Ill: on. the disk.lfifi will engage the roller "18 and cause the armt09' to; forcetheplunger inwardly and close the control circuit through the switch m4.It'i's to be: understood, however. that the circuit closedthroughthe-respectiue switch. [04

be. efieetive to initiate another cycle of move;- Lment of the crankshait It and thereby effect a designated EH dominate'the control of thefurretraction and an advancement of the pusher 24 and an attendantadvancement and retraction of the fuel feeding slide43 only when thepositioning: switches are closed. These positioning switches will bedescribed hereinafter and it is to be understood that they are: closedonly when the: pusher isin its most'advanced position and the fuelfeeding slide: in its fully retracted position.

While it is preferred that the pusher plate 2! always be stopped in itsmost advanced position, and the 'fuel feeding slide in its fullyretracted positiomit is to be understood that the parts can be sotimedas to stop the pusher plate and the slide in any predetermined relati'omShould the parts be timed so that: the pusher plate 2 can: come to restin a. retracted or' partially re traeted position, the feature ofproviding primary air intake ports F5 in the bottom of the fire pot andpusher tunnel only in advance of or forwardly' of the most.- advancedposition of the pusher plate 2* effectively overcomes the possibility ofany fresh coal which might. be disposed in front oi the retractedp'usher plate receiving enough oxygen to burn and fuse or stick to thetunnel floor and by this means jam or tend to jam the: next: forwardmovement of the pusher 7 plate Two additional or auxiliary controlswitches generally designated lfl are provided and each mounted forbeing automatically actuated by movement of the ash discharging door.One such switch; is mounted at each side of the ash discharging door asshown in Figures- 6' and'l.

These switches are so formed and connected in ciprocations of the pusherM and the fuel feeding slide 43: when a fresh fire is being built andbefore a fuel mass. has: been advanced over the fire pol; bottom andinto contact'with the ash euscharglng' door, and also at times when;very rapid combustion provides an excess; of ash. and clinker formationwhich when discharged through the ash door provides a temporary void ora 'minimum'of. fuel mass congestion. resulting ill; a complete closureof the ash discharge door 1 The" particular switch structure illustratedhereim particularly in Figures '6 and 7' ofthe drawings, are of thesame. type illustrated at HM in Figure 13 and includes a-casingl I 2which attached, as at 3, to one of the side plates 62 and a contactmaking and breaking plunger m reciprocable. in and extended from: thecasing." Each plunger is engageable by an actuator H5 fixed to the: ashdoor at the respective side so as; to be moved to its: circuitcompleting position each time the door moves about its pivotal mounting[9 to its: fully closed'position. It is to be understood that; wheneverthe ash discharge *door is in. the closed position ilhlstrated in. Fig?-7 of the drawings, the. switches generally mace and cause the crankshait llto rotate: con- :tinuousim It will: be obvious that if rotationis imparted to this. crank shaft at the; rate of one revolution everytwo minutes, reciprocations will; be imparted; during an hour to thepusher 24 and the fuel feeding slide 4-3: under control domination oithe switch H11. Whenever the feeding, and advancement of iuel bringsabout a sumo-lent fuel mass congestion in the not [0,. the ash;discharge door |8 will be forced open an amount sufficient to cause theswit h Plungers H4; tobreak the dominant. control circuits through theswitches III and re?- store the fast and'slow timer units to normalcontrol of the furnace operation.

The position switch equipments will now be described. An actuator cam H6is mounted upon the'crank shaft II, and this cam is provided with twodiametrically oppositely disposed peripheral recesse ,III, each saidrecess being positioned in a distinctvertical plane traversing the axisof the crank shaft. The cam is adjustably secured upon the crank shaftby a set screw II 8. It is preferred that therecesses II I be sodisposed as to assure stoppage of the pusher 24 and the fuel feedingslide 43 respectively in the fully advanced and fully retractedpositions, but it is to be understood that by reasonpf the adjustablemounting of the cam, stoppage of the parts can be effected with theelements 24 and 43 in any predetermined positions.

A position switch II 9 is associated with the fast timer, and a positionswitch I is associated with the slow timer. Each of these switches is ofthe Well known, normally open or contact spaced type, the contacts beingcaused to engage only when the switch plunger I2I is forced inwardly.Each switch is equipped with an actuator roller I22 supported at thefree end of a yieldable arm I23 overlying the respective plunger I2I andsecured, as at I24, to the switch body. The rollers ride upon theperipheral surface of the cam H6 and are receivable in th recesses I I!previously referred to.

Circuits through the switches H9 and I20 are completed at all timesexcept when the rollers drop into the recesses II! and thereby permitslide 43 is initiated it will be continued .by operation of therespective position switch until these elements have moved through acomplete cycle and have been returned to the starting position, at whichtime the rollers I22 will drop into the recesses III and effect abreaking of the motor circuit;

In Figures 8 and 9 of the drawings, there is illustrated a modified formof the invention in which the dome I25 and thearch I26 are formed ofmetal. In this modified arrangement the arch I26 is equipped with a seatI2'I at its lower edge for removably receiving a fire brick arch I28.Like .the arch previously described, this arch I28 is closely spacedabove the fire pot so as to provide a restricted space I29 for passageof gases and smoke close to the underlying incandescent fire bed. Thearch I28 is provided with a transverse secondary air groove or channelI30 which is supplied with secondary air at one or both ends through anend duct or ducts I3I preferably provided with adjustable plate valveequipment I32.

In Figure 16 of the drawings the electrical control connections of thevarious control devices for use in a furnace adapted for the burning ofsolid fuel other than anthracite are shown. In this illustration thepositive power line is indicated at I33and the negative line at..I34.The positive line is connected at I35 with the pusher and slideactuating motor I3, through the fast timer unit 89, and this line isconnected, as at 7 I36, with saidmotor through the position switch I I9;9 The negative line I34 is connected with the motor I3, as at I31,through the slowtimer unit 90, and this negative lin is likewiseconnected, as at I38, with said motor through the position switch I-20.The fan diagrammatically illustrated at 606I and which serves to supplythe primary and secondary air is connected, as at I39, with theconnections I31 and I38 leading to the motor", and this fan is alsoconnected, as at I40, with the positive power line I33. A thermostat Tis shown as connected as at I4I as a bypass around the slow timer 90.

Figure 1'7 is a view similar to Figure 16 but diagrammaticallyillustrates the control parts as connected for use in a furnace adaptedfor the burning of anthracite coal. In this illustration the thermostatmay be of the form well known and including two simultaneously operablemercury switches diagrammatically illustrated at T and T This thermostatis connected, as at I42, as a by-pass around the slow timer 90, and anadditional fan control timer I43 is connected as at I44, directlybetween the motor and fan assembly Ell -6| and the negative power lineI34. In all other respects this control circuit is identical with theillustration in Figure 16 and is so designated. When anthracite coal isbeing burned in the furnace, it is desirable that the additional I fancontrol timer I43 be included so as to enable the motor and fan assembly60-6I to operate for short periods while the furnace is idling andindependently of the operation of the stoker motor I3.

If desired, the ash discharge gate operated switches generallydesignated I II may be omitted, and in such cases the electricalconnections with the various control devices can be made as illustratedin Figures. 16 and 17. When the ash discharge door operated switches IIIare ineluded, they may be electrically connected in the control circuitsin themanner illustrated in Figure 18. Figure 18 is a view similar toFigure 16 and like electrical connections therein are designated in likemanner as indicated. In this figure, one of the ash discharge dooroperated switches I I I is shown as connected at I45 between thepositive power line I33 and the stoker motor I3 so as'to dominate theposition switch H9 and the fast timer unit 89, and the other of theseswitches III is similarly connected, as at I46, between the negativepower line I34 and the stoker motor I3 so as to dominate the positionswitch I20 and the slow timer unit 90. With the switches III thusconnected in the control circuit, it will be obvious that whenever theash discharge door I8 is'closed the stoker motor I3, and also the fanand fan motor 60-6 I, will be caused to operate continuouslyindependently of the timer units 89-90, the position switches II9I20,and also the thermostat T. In order to avoid operation of the stokermotor and the fan motor when the ash discharge door 'is closed andit isdesired that the furnace should remain out of operation, ,a manuallyoperable circuit breaking switch I4'I may be employed.

It will be apparent that th thermostat serves to effect a selectionbetween the fast and slow fuel feed timing controls. When the thermostatis closed by a heat demand, the current reaches the stoker motor throughthe fast timing control equipment. The, slow timing. control equipmentis notintended. to function .when the fast timing equipment isin controlof the stoker motor operation. Therefore; as long'as the thermostatbypasses the current about the slowtiming control equipment fast timingcontrol. equipment will remain complete control, assuming, of course,the. circuit through theash discharge door operated switches ill isbroken. when such switches are inv use in the system, these switchesbeing in dominant controlwhenever said door is closed. as hereinbef-ore:described The position. of thecontrolling thermostat is determined bythe purpose for which the heating. unit is being used; If the unit: isbeing used for hot water heating, the thermostat will be locatedso as tocut in whenever the temperature in the hot water tank has fallen; belowa predetermined point, and. to cut ofi when said temperature has risenabove. a predetermined point Whenthe heating unit is beingemployed as apart of a hot water heating system a house or apartment, the thermostatwould. be located centrallyin the house or apartment and would.function. in the same manner just above. described with the exceptionthat the medium. controlling the function ofthethermostat would in thiscase be air instead of water as in the previously mentioned case, Inother words, whenever the temperature in the house or apartment roseabove the predetermined. point it would cutthefurnace off, and when itrfell below the predeterminedpointi-twould serve to out the furnace on.However, in. the hot air installation, the thermostat would indirectlycontrol the furnace operation and would be supplemented by a thermostatinstallation. known as a bonnet control. The main thermostat. in thehouse or apartment would control the air circulating fan herei-nbeforereferred to, which would act to raise or lower the bonnet temperatureinthe furnace, and as the tion with a steam or hotv water system, thethermostatwould again operate directly on the stoker to keep the steamorhot water within the predeterminedtemperature limit. It will be apparentalso thatwhen a steam system is employed, it may be found. desirable. tocontrol it with pressure as the factor instead of temperature, in whichcase the system. would include a pressurestatinstead of a thermostat.

Inthe practical operation of the furnace, access may be had to the firepot through the side door 10 and a fire may be laid thereinin the normalway by the common: expedient of laying paper and kindling upon thesupporting bottom I3 and igniting the same, and thereafter supplyingsolid fuel so as to obtain asubstantial fire. After a substantial firehas been obtained, the mechanical control can be resorted to. By closingthe manual switch I41, the ashv discharge door operated switches IIIwill be. placed in control and will cause. the stoker motor 73 and the.fan-motor combination 60-6| to operate continuously until a sufficientamount of fuel has been fed into the fire pot, in successive stages, toengage. and force open the ash discharge. door [8,. at which time thecircuit through the switche [ll will be broken and the normal timingcontrols will takeover the controlling function. Obviously, if there isno heat demand uponthe. thermostat. T at this time, the idling. or slowfeed control equipments. will become. effective. Should the thermostat Tbe closed however, indicatinga demand for heat, the

fast timing equipment beselected to control the operation of the furnaceand the fuelv feeding slide 43 and the. fuel bed advancingpusher-ZA'will be reciprocated the. predetermined number of times per hourcontrolled by this timing equipment until. th heat. demand is:satisfied, at. which time the thermostat. T will/open. and the slowtiming equipment will be placed in control and it will function tosupply just enough fuel to maintain the fire in an idling. condition.regardless ofthe length: of the period preceding the next heat-demand. r7

Once. normal operation of the fire has been achieved, the fast and. slowtiming. equipments alone normally function to control operation of thefurnace, and it. has been found that approximately one-tenth of the.volume of the fuel fed is expelled from the ash discharge door when thefuel being used is. ordinary bitumious coal; This expelled volume is.pure ashes. Should a period of very'rapid combustion result inanabnormal burning of fuel and the formation of a clinker of considerablesize, then, and then only, will the ash discharge door operated switcheslll' function. As a. clinker thus,v formed falls from the ash dischargedoor, it creates a considerable void in the fire; pot and permits. theash discharge door to close- The closing of this door closes the controlcircuits through the switches. I l I and causes them. to dominate thefurnace control as in the continuously until the void is filled and afuel bed congestion established sufiicient to force open the ashdischarge door 13 and. break the circuit through the switches Ill,thereby to return the control of the furnace operation to thenormal'lyfunctioning fast and slow timer equipments;

Assuming that the thermostat T is closed, indicating a demand for heat,and thus selecting the fast timing equipment as the furnace stokingcontrol, current will pass from the positive line I33 through thefast'timer unit 89 (when closed) to the motor 13 and. backthrough thethermostat T to the negative line I34, thus initiating an operation ofthe motor to brin about one complete cycle of operation or the fuelfeeding slide 43 and the pusher 24", namely, a retraction. of the pusheraccompanied by a fuel feeding advancement of the slide, and a retractionof the slide accompanied by an advancement of the pusher to its initialposition. As the pusher plunger 30, moves rearwardly, the fingers 88projecting laterally therefrom. will reset the. two timing switches,breaking the circuits therethrough and restoring energy in the springsI02 as hereinbefore described. Before the circuit, is thus brokenthrough the timing switch 89., initiation of movement. of the crankshaft H will effect a. completion of the circuit through the positionswitch I19 so that the. circuit once completed will be maintained in thecompleted. state by the position switch until. the complete.reciprocation cycle is effected and the slide and pusher are returned.to their initial positions i1lustrated,inFigure I. It will be. notedthat during the fast timer controlled operation of the furnace thecircuit. through the motor and fan assembly 606[ is maintained. throughthe thermostat T so that the fan operates continuously so long as thereis a heat demand.-

When the heat demand is satisfied, the circuit through the thermostat Tis broken and the slow timing equipment is rendered eflective to controlthe operation of.the-furnace.- Aspreviously stated, this slow timingequipment func-,

stat T, and therefore the fan-will operate-imtermittently only, or, inother words, only when the stoker motor 13 is operating. In Figure-l? ofthe drawings; however; there is illustrated, a. modified controlcircuitin which isincluded an additional timer I43 which. may beemployed" when anthracite coal is being burned. to cause the fan tooperate at intervals during the idling operation of the furnace so thatair will .be, supplied tothe combustion chamber at intervalsindependently of the motor.

By reason of the provision of the two fuel-feed rates anrd the twoairsupply rates o ne for, maximum combustionand one for idling, it ispossible to properly adjust the combustion rate for these two conditionsand keep the fire pot in practically uniform condition with only fineash beingdischarged through the ash discharge door It." With theequipment herein illustrated-arid described, it has been found possibleto hold the fire indefinitely while idling ,andat the same time have thefire bed ready to gofull tilt ina few moments after the full air-supplyand fast timing rates go into effect. I The improved furnace structureherein dis,- closed can be readily conditioned forthe use'of any ofvarious types of fuel. This may be done by merely adjusting the ashdischarge door weight 29 and/or by adjusting the feed rate'per hour ofthe new fuel'charges and/or by adjusting the air supply. The feed rateper hour is adjustable either by adjusting the stroke of the feed slide43 in the manner hereinbefore described, or by the readily accessibleand simple adjustment of the timing devices illustrated in; Figures 11to 13 of the drawings whereby-the number of fuel feed strokes per houris controlled. The same furnace can be usedforany size of bituminous oranthracite coal within its range, and can be adjusted quicklyfor lowfusing point coal ash as well as high. 7 In the operation of thefurnace, the rate of feed at high capacity, for mosteconomicaloperation, should never exceed the combustion capacity of the fire potfor the type of. fuel being.

used and for the depth of the fuel bed that is provided. Otherwise,there will be a discharge of unburned fuel into the ash pit.Furthermore, the conditions in the combustionchamber should remainpratically uniform so that.

the air supply can be scientifically adjusted to avoid loss of heatingunused oxygen. Thirdly,

the intensity of the, air blast should not be such.

as to convert the ashes into clinkers. Fourthly.

to prevent all clinker formation'the fuel should not be converted intoash until.just before it is discharged from the combustion chamber.Inthe use of the improved stoking equipment here in disclosed, it ispossible to obtain these advantages in the operation'of the furnace.There.

operation of the stoker can be obtained a condition of economicalequilibrium between fuel supply and combustion rate, which isautomatically maintained and which will provide a fire pot for a burningfuel that becomes ashes only when it has come close to the point ofdischarge at the end of theme pot. The simple adjustmentsand automaticoperations already referred to accomplish these ends. j For any rate offeed which is less than the combustion capacity of the furnace, the firepot will automatically condition itself to certain accumulation of ashesat the discharge end of the fire pot. To the extent that these ashesthus collect, there is a reduction in the combustion area on the firepot bottom, and this reduction in the effective fire pot bottom or gratearea causes automatically a similar reduction in the combustion.capacity of the fire pot which automatically equalizes the combustionrate with the rate of feed of fuel. An equilibrium will thus be attainedregardless of the adjustment of the feed therein. Due to the attainmentof this equilibrium, if the stoker is adjusted so that it is underfed orover-aired, the fire will not go out. There will always be a portion ofthe fire pot which is burning effectively. The only effectof'underfeeding will be that of cutting down the heat justment whichgives the minimum amount of smokeless fashion.

undischarged ash at the end of the fire pot where the least amount ofair is passing through the ashes and not doing its bit in consumingunburned fuel. the combustion chamber represents waste to the extentthat it is not used in completing combustion of gases reachingi-this endof the com bustion chamber.

The particular arrangement of the dome '38 and: the arch 39, and theprovision of therestricted passage 40' directly over the incandescentportion of the fire bed makes it possible to oper atethe hereindisclosed furnace in approximately The successively supplied freshcharges of fuel fallinto the space provided by retraction of the pusher24 at the rear end of the fire pot. These charges are relatively smalland the volatiles and smoke which pass off therefrom move forwardly intheir course toward the flue 31 and are caused to intimately contactwith the incandescent fuel bed portion beneath the restricted outlet 40so as to be consumed. The

incandescent portion of the fuel bed supplies the necessary heat, andthe arch ports 69 the necessary oxygen to provide for the desiredcombustion of thesegases. v

It has been discovered that even without the use of the baffle wall 39and without the use of a secondary air supply, bituminous high volatilecoal burns with extremel little smoke due to the fact that the smallquantity of volatile matter discharged from each of. the small suppliesfed at a time will be consumed in the general combustion of the largecombustion chamber before the next following fresh-fuel supply is fed.Surplus oxygen passing through the fuel bed, or ashes in the fire pot,aids in accomplishing this purpose.

I It will be apparent that the primary air introduced into the fire potis preheated by. drawing the heat away from the side walls of the firepot.-

Air passing through ashes into eluded, other than theelectric motors andmotor gear r'eductions,"on account of the slowness of their movements,will operate in a substantially noiseless manner and present nolubrication prob- 1 lems. Very little power consumption is necessary,and the furnace can operate at a materially 1 reduced repair and powercost for a given output of heat.' A' motor of 1 of a horse-power willsatisfactorily handle all operations except that of the fan for afurnace having a consumption capacity of 25 pounds of bituminous coalper hour. A positive feed cycle is provided. Set timings operate thisfeed cycle for both high capacity and for idling at an invariable ratefor an approximately invariable amount of feed per hour. Therear'e,however, combined with the preliminary setting of the feed rates forhigh capacity and idling, the automatic features referred to whichprovide uniform conditions in the fire not at both extremes of thecombustion rate. The con'diticnsinside the fire not will comets anequilibrium according to'the way the controls areset, and the setting ofthese controls thereafter automatically regulates the available amountof combustion in the fire pot and the nature of discharge from thedischarge end of the fire pot according to the pleasure of the operator.

In our improvedfurnace, means is provided for effecting an automaticdelivery of the ashes :through the'discharge end of the fire pot. In theoperation of the furnace, there is no extensive accumulation of ashesexcept at the dischargeend of the'fire pot, and inthis way a practicallyuniform condition of the combustion zone is maintained at all times sothat the air supply can be perfectly adjusted to the fuel supply and sothat there will be noexcess of air provided. By checking the analysis ofthe stack gases it is possible to determine whether or not too large aquantity of air is being supplied for the amount of fuel being fed, etcetera. By reason of the provision of the equipment herein shown anddescribed, a scientificadjustment can be effected which will be perfectas long as this adjustment is maintained and the same type of fuel isused, and when the type of fuel'is changed the necessary re-adjustmentcan be readily and easily. effected. The uniform fire pot conditionswhich are in equilibrium with the air supply pertain whether the stokeris running at full capacity or idling. There will. be no intermediateperiods of conditions during which the high capacity of the combustionexperiences any appreciable variations. t

The provision of the downwardly sloping bottom in the .fire pot renderspossible the use of a relatively long fire pot and the provision of 'alarge grate area fora certain width of fire pot without increasing thedepth of the fire bed unduly. By controlling the downward slope of thebottom of the fire pot where the fire pot is relatively long, it ispossible to yieldably close the discharge gate l8 and obtaineffectivecontrol by itsuse and atthe same time keep down the depth of'the fuelbed to a reasonable point.

It is of course to be understood thatthe details of structure andarrangement of parts may be variouslychanged and modified withoutdeparting from the spirit and scope 'of the invention as pointed outinthe appended claims. 4

We claim; y 1. In a furnace, a longitudinal fire pot having 10 areceiving end and an end portion over which ash'and clinker can bedischarged and including a fuel mass supporting bottom and fuel massretaining side walls, a pusher'reciprocably mount ed at the fresh fuelreceiving end of the fire pot l5 remote from said discharge end foradvancing freshfuel charges and fuel mass along the fire pot,'a freshfuel hopper having a discharge throat disposed above and adjacent saidreceiving end, a fresh fuel charge pushing slide reciprocable at leastpart way across saidthroat for feeding successive charges of fuel intothe space formed'by each retraction of the pusher, driving means forsaid pusher and slide, and control means for au-' tomaticallycontrolling operation of said driving means responsive to heat demandsand including devices for causing the pusher and slide always to stop ina predetermined position.

2. In a furnace, a longitudinal fire pothaving a receiving end and anend portion over which ash and clinker can bedi'scharged and includingafuel mass supporting bottom and fuel mass retaining side walls, apusherreciprocably mounted at the fresh fuel'receiving end of the firepot remote from said discharge end foradvancing fresh fuel charges andfuel mass along the fire pot; a fresh fuel hopper having a dischargethroat disposed above and adjacent said receiving end,

a fresh fuel charge pushing slide reciprocable at 7 least part wayacross said throat for feeding successive charges of fuel into the spaceformed by each retraction of the pusher, driving means for said pusherand silde. and selective control means responsive to heat demands forcontrolling operation of said driving means for feeding a predetermineddefinite number of fuel-charges into thefire pot in a given interval oftime and in ad- Vance of the pusher to be pushed along the bottomthereby for maximum combustion operation of the furnace, or forsimilarly feeding a predetermined definite lesser number of fuel chargesinto the'fire pot in the same given interval of time for idlingoperation of the furnace.

3. In a furnace, a longitudinal fire pot having a receivin end and anend'portlon over which 55' ash and clinkercan be discharged andincluding a fuel mass supporting bottom and fuel mass retaining sidewalls, a pusher reciprocably mounted at the fresh fuel receiving end ofthe fire pot remote from said discharge end for advancing go fresh fuelcharges and fuel mass along the fire pot, a fresh fuel hOliper having adischarge throat disposed aboveand adjacent said receiving end,

a' fresh fuel charge pushing slide reciprocable at least part wayacrosssaid throat for feeding successive charges offuel into the spaceformed by each retraction of the pusher,'driving means for said pusher;and slide, selective control means responsive to heat demands forcontrolling operation of said driving means for feeding apredenjtermined definite number of fuel charges into the fire pot in a,given interval of time and in advanceof the pushe'rto be pushed alongthe bottom thereby for maximum combustion operation of the furnace, orfor similarly feeding a predetermined definite lesser number of fuelcharges into the fire pot in the same given interval of time for idlingoperation of the furnace, means for varying the amount of fuelcomprising each fuel charge, a swingably mounted gate for yield ablyresisting passage of ash and clinkers through the discharge end of thefire pot, and adjustable means for settingrup a variable resistance toopening of said gate. p

4. In a furnace, a longitudinal fire pot having a receiving end and anend portion over which ash and clinker can be discharged and including afuel mass supporting bottom and fuel mass retaining side walls, a pusherreciprocably mounted at the fresh fuel receiving end of the fire potremote from said discharge end for advancing fresh fuel charges and fuelmass along the fire pot, a fresh fuel hopper having a discharge throatdisposed above and adjacent said receiving end, a fresh fuel chargepushing slide reciprocable at least part way across said throat forfeeding successive charges of fuel into the space formed by eachretraction of the pusher, driving means for said pusher and slide,selective control means responsive to heat demands for controllingoperation of said driving means for feeding a predetermined definitenumber of fuel charges into the fire pot'in a given interval of time andin advance of the pusher to be pushed along the bottom thereby formaximum combustion operation of the furnace, or for similarly feeding apredetermined definite lesser number of fuel charges into the fire potin the same given interval of time for idling operation of the furnace,a swingably mounted gate for yieldably resisting passage of ash andcli'nke'rs through the discharge end of the fire pot, and additionalcontrol means effectivewhenever said gate is fully closed to dominatethe other controls and cause the drivin means to operate continuously tofeed successive charges of fuel until the gate is opened a predeterminedamount by ash or clinker accumulation discharge therethrough.

5. In a furnace, a longitudinal fire pot having a receiving end and anend portion over which ash and clinker can be discharged and includingleast part way across said throat for feeding successive charges of fuelinto the space formed'by each retraction of the pusher, driving meansfor said pusher and slide, selective control means responsive to heatdemands for controlling operation of said driving means for feeding apredetermined definite number of fuel charges into the firepot in agiven interval of time and in advance of the pusher to be pushed alongthe bottom thereby for maximum combustion operation of the furnace, orfor similarly feeding a predetermined definite lesser number of fuelcharges into the fire pot in the same given interval of time for idlingoperation of the furnace, and means including a fan for supplying airfor combustion to the fire pot continuously during maximum combustionoperation of the furnace and intermittently during idling operation ofthe furnace.

7. In a furnace, the combination of a longitudinal fire pot having areceiving end and an end portion over which ash and clinker can bepushed and discharged and also having a fuel mass supporting bottom andfuel mass retaining side walls, a reservoir for solid fuel supportedbeyond said receiving end and having a discharge throat located higherthan the normal level of burning fuel in the fire pot, a fuelmass pusherreciprocable in the direction of the length of the fire pot with itsface serving at least in part as a rear closure for said pot and bearingconstant upright a fuel mass supporting bottom and fuel mass re- 7taining side walls, a pusher reciprocably mounted at the fresh fuelreceiving end of the fire pot remote from said discharge end foradvancin fresh fuel charges and fuel mass along the fire pot, a freshfuel hopper having a discharge throat disposed above and adjacent saidreceiving end, a fresh fuel charge pushing slide reciprocable at least.part way across said throat for feeding successive charges of fuel intothe space formed by each retraction of the pusher, and means for movingthe pusher and slide in timed relation, said last named means includinga rotary crank shaft and driving connections between the crank shaft andsaid pusher and slide and control devices for causing the crank shaft toturn in identical individual successive cycles thereby to always leavethe pusher and slide in the same position following completion of eachcycle.

6. In a furnace, a longitudinal fire pot having a receiving end and anend portion over which ash and clinker can be discharged and including afuel mass supporting bottom and fuel mass retaining side walls, a pusherreciprocably mounted at the fresh fuel receiving end of the fire potremote from said discharge end for advancing fresh fuel charges and fuelmass along the fire pot, a fresh fuel hopper having a discharge throatdisposed above and adjacent said receiving end, a fresh fuel chargepushing slide r'eciprocable'at angular relation to said bottom and.effective when moved forwardly to push fuel mass before it over saidbottom and when retracted to provide afresh fuel receiving pocketbetween said face and said fuel mass, a feed plunger reciprocable atleast;part way across said throat in a path substantially parallelingthe path of movement of the pusher and above said level of burning fuelfor feeding fuel from said throat to fall, by gravity into said pocket,means operable during maximum heat demands forcontinuously reciprocatingand timing said pusher and feed plunger so that the latter movesforwardly when the former is retracted, means for varying the stroke ofthe feed plunger to vary the amount of fuel forced to fall into saidpocket on each forward movementthereof, baffie means disposed forwardlyof the feed plunger and shielding fuel in the throat and reservoir fromheat in'the pot,

and means for continuously and regulatably introducing air into the firepot to support combustion therein.

8. A furnace structure as defined in claim 7 in which there is includeda gate having fiexible fingers disposed across the reservoir throat toretain fuel therein when the feeder plunger is being retracted andthrough which fuel charges can be forced by the feed plunger to fall bygravity into the fire pot, and which can fiex to conform about fuellumps and prevent sifting through of fine fuel from said throatat thesides of said lumps.

9. A furnace structure as defined in claim '7 in which the pusher andthe feeder plunger are so constructed and cooperatively arranged thatthe pocket formed by retraction of said pusher always is larger than thevolume of a fuel charge fed by forward movement of the feed plunger I sothat successively fed charges of fresh fuel do comprises adjustable lostmotion connections in the continuously Operating reciprocating andtiming means. I r

11. A furnace structure as defined in claim 7 in Which'the fire potbottom has apertures which are hooded in the direction toward thedischarge end and throughwhich the combustion supporting air isdirected, thereby to prevent free falling of ash through said aperturesand causingsubstantially .all ashes or solid products of combusinwhich'the center of thefuel engaging pusher face of the pusher liessubstantially in the same vertical longitudinal plane as the center ofthe fuel engaging face of the feed plunger. 7

A furnace structure as definedin claim 7 in'which the pusher and thefeed plunger are reciprocated synchronously by a single source ofmechanical power. r

16. A furnace structure as defined .in claim '7 in which there isprovided a throat floor over which the feed plunger moves andin whichthe pusher has a generally horizontal top portion, said fioor beingspaced above the pusher top portion by a member contacted by' air fromoutside the furnace thereby to retain a relatively cool condition ofsaid member and insulate the fuel engaging face of the feed plunger fromthe heat of'the pusher.

17. A furnace structure as defined in claim '1 in which the pusher has agenerally horizontal top portion, and in which the throat shieldingbafile means includes an element portion reaching down approximately tothe. level of said pusher top portion. 7 7 18. A furnace structure asdefined in claim 7 in which there is provided a throat floor over whichthe feed plunger moves and in which the throat shielding baflle meansincludes a swingably mounted gate suspended over said floor with itslower free edge portion disposed adjacent said floor.

19. A furnace structure as defined in claim 7 in which there is includedmeans for yieldably resisting ash discharge from the discharge endportion of the fire .pot bottom, and means for varying the amount ofsaid resistance.

20. In a furnace, a longitudinal fire pot having a receiving end and anend portion over' which ash and clinker can be discharged and includinga fuel mass supporting bottom and fuel mass retaining side walls, meansfor mov- 1 ing fresh fuel charges and fuel mass along said bottom towardsaid discharge end, said side walls having primary air openingstherethrough and extending along the fire pot just above said bottom,said bottom having openings therethrough, 1 casing structure soconstructed and arranged as to form a primary air delivery chamberdisposed beneath the bottom for directing primary air upwardlytherethrough and extending upwardly laterally of said side wall portionsinto position for communicating with said side wall openings to directsaid air into the side wall openings.

21. In a furnace, a longitudinal fire pot having a receiving end and anend portion over which ash and clinker can be discharged andincluding afuel mass supporting bottom and. fuel mass retaining side walls, meansfor moving fresh fuel charges and fuel mass along said bottom towardsaid discharge end, said side walls having primary air openingstherethrough and extending along thefire pot just above said bottom,said bottom having openings therethrough, casing structure soconstructed and arranged as to form a primary air-delivery chamberdisposed beneath the bottom for directing primary air upwardlytherethrough and extending upwardly laterally of said side wall portionsand then downwardly parallel and against said side wall portions intoposition for communicating with said side wall openings to project asheet of air in preheating contact with each said side wall portionprior to entry through the side wall openings into the fire bed on thefuel mass supporting bottom.

22. In a furnace, a longitudinal fire pot having a receiving end and anend .oVer which ash and clinker can be discharged nd including a fuelmass supporting bottom and fuel mass retaining side walls, a pusherreciprocably mounted atthe receiving end of the fire pot remote fromsaid discharge end for feeding fuel mass along the fire pot, a freshfuel hopper having a discharge throat, means supporting said hopper withits discharge throat disposed above and adjacent said receiving end, afresh fuel charge pushing slide reciprocable at least partway acrosssaid throat for feeding successive charges of fuel from said throat tofall by gravity into the space formed by each retraction of the pusher,a yieldable gate, means for supporting said gate across said throat inposition for being normally effective to hold fuel in the throat, saidgate including a plurality'of depending closely related spring fingersyieldable to permit passage of fuel being pushed by said slide, andmeans for moving the pusher and the slide in timed relation.

2,3. Ina furnace, the combination defined in claim 22 in which isincluded a flap swingably mounted between the yieldable gate and thefire pot for shielding fuel in the hopper from radiant heat from thefire pot. I

24. .In a furnace, a longitudinal fire pot having a receiving end and anend overwhich ash and clinker can be discharged and includin a fuel masssupporting bottom and fuel mass re tainingside walls, a pusherreciprocably mounted at the receiving end of the fire pot remote fromsaid discharge end for feeding fuel mass along the fire pot, a freshfuel hopper having a discharge throat, means supporting said hopper withits discharge throat disposed above and adjacent said receiving end, afresh fuel charge pushing slide reciprocable at least part way acrosssaid throat for feeding successive charges of fuel from said throat tofall by gravity into the space formed by each retraction of the pusher,a yieldable gate, means for supporting said gate across said throat inposition for being normally effective to hold fuel in the throat, saidgate includinga plurality of depending closely related spring fingersyieldable to permit passage of fuel being'push'ed by said slide, andmeans for moving the pusher and the slide in timed relation, said lastnamedmeans including a rotary crank shaft having two cranks thereon, alever pivoted at one end and connected .at its other end with the slide,a lever pivoted at one end and connectedat its other end

